.github: update actions to Node.js 24

All workflow runs now warn:

    Node.js 20 is deprecated. The following actions target Node.js 20
    but are being forced to run on Node.js 24.

Update the actions/* dependencies to their current major versions,
all of which target Node.js 24: checkout v7, upload-artifact v7,
download-artifact v8, setup-python v7, and cache v6.  The release
action tracks the floating v1 tag and updates on its own.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

.github/workflows/weekly.yml

@@ -16,7 +16,7 @@ jobs:
     outputs:
       branches: ${{ steps.schedule.outputs.branches }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v7
         with:
           fetch-depth: 0
       - name: Check for branches with no commits since last week
@@ -51,7 +51,7 @@ jobs:
           (cd libuev-2.4.1 && ./configure && make -j9 && sudo make install-strip)
           (cd libite-2.6.2 && ./configure && make -j9 && sudo make install-strip)
           sudo ldconfig
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v7
         with:
           ref: ${{ matrix.branch }}
       - name: Base run
@@ -72,7 +72,7 @@ jobs:
           make -j1 distcheck || (cat $dir/test/test-suite.log; false)
       - name: Upload Test Results
         if: always()
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v7
         with:
           name: finit-weekly-test-logs-${{ matrix.branch }}
           path: finit-*/_build/sub/test/*.log